Dynamic polymeric materials via hydrogen-bond cross-linking: Effect of multiple network topologies

Hydrogen bonds (H-bonds) exhibit excellent reversibility, high orientation, and flexible designability among all dynamic non-covalent bonds (DNBs). Herein, the effect of multiple network topologies (including single/double/triple cross-linked networks) in H-bond based dynamic polymeric materials (DPMs) is summarized with the structural design strategies and molecular mechanisms. Additionally, their potential applications in improving mechanical properties, self-healing capabilities, and biomedical fields are also presented in this paper. The first part introduces the basic design principle of single physically cross-linked networks formed by H-bonds. Influenced by the low mechanical strength of H-bonds, the tunability and designability of single H-bonded networks are limited. The second part focuses on the double cross-linked networks via H-bonds and other dynamic interactions, the strategy of exploiting the synergistic enhancement of double networks can improve the comprehensive performance of materials considerably. Then, the third and fourth parts briefly introduce the research progress of triple cross-linked networks and the biomedical applications of H-bond based DPMs. Finally, the development trend of H-bond based DPMs is predicted based on the above groundbreaking and representative research results.